Rope tow



R. D. WATT Dec. 7, 1965 ROPE TOW ROBERT D. WATT INVENTOR E ATTORNEYSDec. 7, 1965 R. D. WATT 3,221,667

ROPE Tow Filed April 13, 1964 n 2 Sheets-Sheet 2 ROBERT D. WATTINVENTOR,

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ATTORNEYS United States Patent O 3,221,667 ROPE TOW Robert D. Watt,Seattle, Wash., assignor to Electro-Watt, Inc., Seattle, Wash., acorporation of Washington Filed Apr. 13, 1964, Ser. No. 359,293 9Claims. (Cl. 104-173) This application relates to ski tows, andparticularly that type of ski tow commonly known as a rope tow. Ropetows are characterized in that the skier grips a bare rope, riding hisskis while pulled by such rope up a slope. The rope is endless, passingover a sheave or sheaves at each end limit of the run.

Rope tows as heretofore known have not been acceptable as approvedequipment in many skiing areas from the fact that the ropes have beensubject to twisting. This can be quite dangerous in that a users wriststrap, glove, or sleeve can become caught between strands of thetwisting rope. The twisting is attributable A to the reaction of thelays of the rope as the rope bears against a sheave, or more especiallya flange of the sheave,

in passing over the sheave. For its principal object the presentinvention aims to provide a rope tow having a perfected sheave assemblyso constructed and arranged ,that twisting of the rope can besubstantially obviated. With this and other objects and advantages inview which A teachings of the present invention.

FIG. 2 is a fragmentary horizontal sectional view q drawn to an enlargedscale on line 2--2 of FIG. l.

FIG. 3 is a fragmentary transverse vertical sectional I view on line 3-3of FIG. 2; and

FIG. 4 is a fragmentary longitudinal vertical sectional view on line 4 4of FIG. 3.

In said drawings, and rst having reference to FIG. 1, i

the numerals 10 and 11 denote mounting posts the former located at thedown-hill end and the latter located at the up-hill end of a ski slope.An endless lpower-driven tow rope 12 extends between the two poles,being trained about sets of sheaves 4to provide a lower-level tow runand an upper-level return run. As here shown, the uphill set iscomprised of two vertically spaced sheaves 13 and 14. The down-hill setis comprised of six sheaves 15, 16, 17, 18, 19 and 20. The sheave 18 isa live sheave driven from a power plant 21 sheltered by a house 22. Eachof the other sheaves is free-running.

Generally considered, the several sheaves all occupy a common verticalplane, with the sheaves of the lowerlevel set so placed that the returnrun of the rope 12 rst passes under the sheave 15, and thence takessuccessive bights about the sheaves 16, 17, 18 and 19 before passingdownwardly to and about the sheave 20. Sheave 16 is carried by acarriage 23 mounted upon a guide rod 24 for slide movement in adirection endwise to the ski slope, and is ten-sioned, so as to maintainthe rope in a taut condition, by a weight 25.

For a purpose which will hereinafter appear, the down-hill sheave 20 andeach of the two up-hill sheaves 13 and 14 receive their support fromrespective brackets, as 26, 27 and 28, which are attached to respectiveI-beams 30, 31 and 32. They are each so mounted that the plane in whichthe respective sheave lies can be canted within prescribed limits ineither direction from center, and set at any selected point within thepermitted range of this prescribed movement. The individual mounting ismuch the same for each of said three sheaves and a detailed 3,221,667PatentediDec. 7, 1965 ice description of the sheave 13 will thus suicefor the sheaves 14 and 20.

I-beam 31 lies perpendicular to the ground and is welded or otherwiserigidly secured to the post 11. Bracket 27 is or may be a fabricatedstructure and at the back provides vertically spaced claw-feet 33arranged to be slipped onto the outer llange 34 of the I-beam. Theexposed front face 35 of the bracket is vertically elongated and flat,and occupies a plane normal to the plane in which the two runs of therope lie. Two threaded studs 36 and 37 are made rigid with the bracketand project forwardly beyond said face 35, one adjacent the upper endand the other adjacent the lower end thereof.

A swing-plate 40 seats upon the face 35, having at its upper end apivot-hole 4-1 to t over the upper stud 36 .and at its lower end lanarcuate slot 42 developed about the drill-hole as a center and ttingover the stud 37. Holding the swing-plate to the bracket are sets ofjamnuts 43 and 44, with the former being applied to the stud 36 andbearing through a washer 47 upon a spacer 48, and the latter beingapplied to the stud 37 and bearing upon a cross-head 50. Set screws 51and 52 threadably carried by lugs 53 and 54 located beyond the two endsof the slot bear upon diametrically opposite flats of the cross-head topermit said cross-head to be set at a selected adjusted position betweenlimits prescribed by the slot.

Upstanding cheeks 55 project forwardly from the swing-plate `at oppositesides of the pivot-hole 41, and drilled through such cheeks on acoinciding transverse axis lying normal to the plates major axis andpreferably placed so as to give little more than bare clearance relativeto the spacer 48 are holes accommodating a crosspin 56. Pivoted fromthis cross-pin is a yoke having its arms 57 rigidly connected by across-bar 58. The sheave 13 is received between said arms of the yoke,being journaled upon a spindle 59 for free rotation about an axisparalleling that of the cross-pin 56.

The brackets for the two sheaves 20 and 13 are each slidably adjustableupon the related I-beam, being set in the desired position by means suchas the indicated chains 60. Inner ends of these chains are hooked ineyes 61 which are provided at the upper and lower ends of the bracket.Outer ends of the chains engage suitable catches provided at the upperand lower ends of the I-beam. The purpose of this adjustment is to placethe lower or tow run of the rope at a desired elevation above the snowlevel. Substantial changes in the snow level require compensatingvertical adjustment of the brackets for the two lower sheaves. Should itbe desired, the bracket for the upper sheave 14 can be welded in placein that this sheave does not require vertical adjustment.

An operator in adjusting the rope tow so as to obviate the objectionabletwisting, first backs off both set screws from the cross-head of theupper sheave 14. This allows the swing-plate for such sheave to hunt, soto speak, as adjustment is being made to the two lower sheaves 20 and13. It has been found that this hunting positions sheave 14 in itsproper plane as an automatic consequence of the lower-level adjustment.When the latter adjustment has been completed, the set screws for theupper sheave are set against the cross-head.

The 'lower-level swing adjustment is perforce made by taking up on oneor the other of the two set screws 51 and 52, responsively canting theplane of the concerned sheave in a direction such as to im-pose upon therope, from the anges of the sheave, a pressure which will work counterto any twist which the rope exhibits. The twist, working back along therun of a rope from a sheave over which the rope is trained, can be ineither a clockwise or a counter-clockwise direction depending upon whichof a sheaves flanges imposes dominating pressure upon the lays of therope. Trial and error allows an operator to ascertain the particulardegree of cant, in one direction or the other from center, necessary toneutralize ange pressure.

It is believed that the invention will have been clearly understood fromthe foregoing detailed description of my now-preferred illustratedembodiment. Changes in the details of construction may be resorted towithout departing from the spirit of the invention and it is accordinglymy intention that no limitations be implied and that the hereto annexedclaims be given the broadest interpretation to which the employedlanguage fairly admits.

What I claim is:

1. In a rope tow, a set of sheaves including two pairs of guide sheavesone pair for the up-hill end and one pair for the down-hill end of a skislope, individual mountings providing rotary journals for the two guidesheaves of each pair and placing the two sheaves one above another inlongitudinal vertical planes which generally coincide, an endlesspower-driven tow rope of the twisted character trained over said set ofsheaves and in its travel over the guide sheaves tracing a generallyrectangular course rst working downwardly from the upper to the lowersheave of the down-hill pair, thence progressing on a lower-level towrun to the lower sheave of the up-hill pair, and then working upwardlyto the upper sheave of said up-hill pair before making an upper-levelreturn run, the mountings for at least the lower sheaves in said twopairs of guide sheaves being each carried for adjusting swivel motionabout a respective horizontal axis located normal to the concernedjournal axis, and means for setting said adjustable mountings atselected points within a permitted range of swivel motion.

2. A rope tow according to claim 1 in which the mounting for the uppersheave of said up-hill pair is also carried for adjusting swivel motionabout a horizontal axis normal to the concerned journal axis.

3. A rope tow according to claim 1 in which the mountings for said lowerguide sheaves are vertically movable, and have means for setting thesame at selected points within a given range of permitted verticalmovement.

4. A rope tow according to claim 3, standards being provided at theup-hill and down-hill ends of the ski slope, said standards eachproviding a vertical slide-way, `the adjustable Vmountings comprisingbrackets carried for slidemotion by the slide-ways.

5. A rope tow according to claim 1, standards being provided at theup-hill and down-hill ends of the ski slope, said standards eachproviding a vertical slide-way, the adjustable mountings comprisingbrackets carried for slide motion by the slide-ways and each having astud rigid therewith and extending horizontally inwardly of the coursein the approximate plane of the rope tow, a respective yoke for eachsheave having the sheave journaled for rotation in the space between thearms of the yoke, and a respective plate to which each yoke is attachedpivoted for swing motion to the stud of the concerned bracket, the meansfor setting said mounting comprising: a second stud rigid with theconcerned bracket and located in offset paralleling relation to thepivot stud and Working in a slot provided in the swing-plate anddeveloped on an arc having the pivot stud as its center, a cross-headfitting over said second stud, and opposing set screws carried by theswing-plate at opposite sides of the second stud and bearing againstflats provided by the cross-head.

6. A rope tow according to claim 5 characterized in that the attachmentof each yoke to its swing-plate places the rotary axis of the concernedsheave in close proximity to the horizontal plane in which thepivot-stud lies.

7. A rope tow according to claim 5, the attachment of each yoke to itsswing-plate being a pivot attachment allowing vertical swing motion ofthe yoke about a horizontal axis located in close proximity to thepivot-stud.

8. A rope tow according to claim 5 in which the yokes position theconcerned sheaves so that the plane which each sheave occupies containsthe swing axis of the related swing-plate.

9. In a rope tow, a set of sheaves including two pairs of guide sheavesone pair for the up-hill end and one pair for the down-hill end of a skislope, individual mountings providing rotary journals for the two guidesheaves of each pair and placing the two sheaves one above another inlongitudinal vertical planes which generally coincide, an endlesspower-driven tow rope of the twisted character trained over said set ofsheaves and in its travel over the guide sheaves tracing a generallyrectangular course rst working downwardly from the upper to the lowersheave of the down-hill pair, thence progressing on a lower-level towrun to the lower sheave of the up-hill pair and then working upwardly tothe upper sheave of said up-hill pair before making an upper-levelreturn run, the mountings for at least the lower sheaves in said twopairs of guide sheaves being each carried for adjusting motionpermitting the sheave to be placed so that the longitudinal verticalplane which it occupies lies either parallel with or canted in eitherlateral direction from the longitudinal vertical plane which the relatedupper sheave occupies, and means for setting said adjustable mountingsat selected points within a permitted range of said adjusting motion.

No references cited.

MILTON BUCHLER, Primary Examiner.

1. IN A ROPE TOW, A SET OF SHEAVES INCLUDING TWO PAIRS OF GUIDE SHEAVESONE PAIR FOR THE UP-HILL AND ONE PAIR FOR THE DOWN-HILL END OF A SKISLOPE, INDIVIDUALLY MOUNTINGS PROVIDING ROTARY JOURNALS FOR THE TWOGUIDE SHEAVES OF EACH PAIR AND PLACING THE TWO SHEAVES ONE ABOVE ANOTHERIN LONGITUDINAL VERTICAL PLANES WHICH GENERALLY CONCIDE, AN ENDLESSPOWER-DRIVEN TOW ROPE OF THE TWISTED CHARACTER TRAINED OVER SAID SET OFSHEAVES AND IN ITS TRAVEL OVER THE GUIDE SHEAVES TRACING A GENERALLYRECTANGULAR COURSE FIRST WORKING DOWNWARDLY FROM THE UPPER TO THE LOWERSHEAVE OF THE DOWN-HILL PAIR, THENCE PROGRESSING ON A LOWER-LEVEL TOWRUN TO THE LOWER SHEAVE OF THE UP-HILL PAIR, AND THEN WORKING UPWARDLYTO THE UPPER SHEAVE OF SAID UP-HILL PAIR BEFORE MAKING AN UPPER-LEVELRETURN RUN, THE MOUNTINGS FOR AT LEAST THE LOWER SHEAVES IN SAID TWOPAIRS OF GUIDE SHEAVES BEING EACH CARRIED FOR ADJUSTING SWIVEL MOTIONABOUT A RESPECTIVE HORIZONTAL AXIS LOCATED NORMAL TO THE CONCERNEDJOURNAL AXIS, AND MEANS FOR SETTING SAID ADJUSTABLE MOUNTINGS ATSELECTED POINTS WITHIN A PERMITTED RANGE OF SWIVEL MOTION.